Packing seals

Claim 1

A railroad angle cock including a housing having a generally cylindrical inlet chamber and an outlet, a valve member positioned within said housing for controlling communication between said inlet chamber and said outlet, a generally cylindrical seal member confined in said chamber and subjected to compression in an axial direction, said seal member having a pair of spaced peripherally extending annular grooves about the exterior thereof, each of said grooves being generally semicircular in shape and having a depth generally equal to one-half the thickness of the seal member, said grooves being spaced inwardly from the ends of the seal member a distance generally equal to the width of the grooves, said grooves having an outer width generally equal to the thickness of the seal member, the length of the seal member being generally equal to one-half of its diameter, axial compression applied to said seal member causing the groove sides to move toward a closure and causing the central area of said seal, between the grooves, to be distorted outwardly and the ends of the seal, adjacent the grooves, to be distorted inwardly to provide firm seals with the inner and outer axIally extending walls of the chamber, said seal being formed of a material such that low temperature shrinkage causes said grooves to tend to open and said seal to bow outwardly adjacent the center to provide a firm seal at the central area of the chamber outer wall and firm seals at the ends of the seal, adjacent the grooves, with the chamber inner wall.